Adsorption of residual trace impurities in UPW onto wafer surface

The state-of-the-art UPW (Ultra Pure Water) production technology has reduced almost all impurities in UPW below their determination limit. Trace metals still remaining in UPW, however, are considered to adversely affect yield of semiconductor device that has been hitting the theoretical limit. Integral adsorption method is a means to accurately measure trace impurities in UPW by concentrating and getting them adsorbed onto Si substrate. By using this method, authors precisely studied behavior of residual trace impurities in UPW and have revealed that they are highly likely to form impurity complexes by coagulating with colloidal matters or organic impurities.